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| Home > Publications database > Modellierung der Bildung und des Wachstums von H$_{2}$SO$_{4}$/H$_{2}$O Aerosolen in der Stratosphäre und oberen Troposphäre |
| Dissertation / PhD Thesis/Book | PreJuSER-24997 |
2001
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
Please use a persistent id in citations: http://hdl.handle.net/2128/19984
Report No.: Juel-3884
Abstract: The aim of this thesis was the development of a spectral box model for quantitative simulations of formation and growth processes of stratospheric aerosols under various atmospheric conditions. The model considers the microphysical processes of binary homogenous nucleation of H$_{2}$SO$_{4}$ and H$_{2}$O, Brownian coagulation and the diffusive gas uptake of HNO$_{3}$ and H$_{2}$O on the liquid sulfate aerosol. To test the microphysical processes implemented in the model sensitivity studies have been performed, e. g. the HNO$_{3}$ uptake under polar stratospheric conditions and the formation of aerosol particles under enhanced H$_{2}$SO$_{4}$ concentrations in the stratosphere, e. g. after a volcanic eruption. To verify the model results of the coagulation process these have been compared to an analytical solution and to other models. The sensitvity studies show that formation and growth processes of stratospheric aerosols can be quantitatively described by the box model under unperturbed and perturbed conditions. Subsequent to the sensitivity studies the microphysical box model has been used to investigate condensation and growth processes during STREAM 1998 (Stratosphere-Troposphere Experiments by Aircraft Measurements) campaign. The box model results demonstrate that the particles which have been formed and dehydrated the atmosphere have an other composition than H$_{2}$SO$_{4}$/H$_{2}$O and H$_{2}$SO$_{4}$/H$_{2}$O/HNO$_{3}$, respectively. Studies of mixing-induced formation of aerosols show that mixing of two air parcels with different initial temperatures and humidities can cause a. significant enhancement of nucleation and condensation rates. Enhancements of nucleation rates up to nine orders of magnitude can occur. Since mixing of two air parcels generates high supersaturations also the condensation rate will be enhanced. Additionally, isentropic transport of H$_{2}$O through the subtropical tropopause has been simulated with CLaMS (Chemical Lagrangian Model of the Stratosphere) to investigate processes which are responsible for the con servation of the water vapour distribution measured by HALDE (Halogen Occultation Experiment). The CLaMS results show that mixing and condensation processes can contribute to the conservation of the water vapour distribution.
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